This investigation is a two-part study. The first part of this program is to establish the tumor incidence in the progeny of Wistar rats exposed to diethylstilbestrol prenatally on days 16-20. The second part of this study is to examine the mechanism by which this tumorgenesis is produced. Currently,, maternal placental and fetal organs are being examined both in vivo and in vitro to establish the metabolites of diethylstilbestrol - both oxidative and conjugates and the interactions of diethylstilbestrol and/or its metabolites with cellular components.